U.S. patent application number 16/645832 was filed with the patent office on 2020-06-25 for method for determining a maximum speed of a vehicle during a parking maneuver.
The applicant listed for this patent is Robert Bosch GmbH. Invention is credited to Thomas Brettschneider, Andreas Englert, Toni Frenzel, Lukas Oppolzer, Tobias Putzer.
Application Number | 20200198621 16/645832 |
Document ID | / |
Family ID | 63490415 |
Filed Date | 2020-06-25 |
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United States Patent
Application |
20200198621 |
Kind Code |
A1 |
Englert; Andreas ; et
al. |
June 25, 2020 |
METHOD FOR DETERMINING A MAXIMUM SPEED OF A VEHICLE DURING A
PARKING MANEUVER
Abstract
A method for determining a maximum speed of a vehicle during a
parking maneuver, in which at least one surroundings condition is
detected with the aid of at least one sensor unit and supplied to a
control unit as an input variable.
Inventors: |
Englert; Andreas; (Suzhou,
CN) ; Oppolzer; Lukas; (Heilbronn, DE) ;
Brettschneider; Thomas; (Suzhou, CN) ; Putzer;
Tobias; (Flein, DE) ; Frenzel; Toni;
(Yokohama-Yokohama-Shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Robert Bosch GmbH |
Stuttgart |
|
DE |
|
|
Family ID: |
63490415 |
Appl. No.: |
16/645832 |
Filed: |
August 22, 2018 |
PCT Filed: |
August 22, 2018 |
PCT NO: |
PCT/EP2018/072609 |
371 Date: |
March 10, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60T 17/221 20130101;
B60T 2220/04 20130101; B60T 2210/32 20130101; B60T 2210/20
20130101; B60W 2554/801 20200201; B62D 15/0285 20130101; B60W 30/06
20130101; B60W 2552/40 20200201; B60W 2554/802 20200201; B60W
2552/15 20200201; B60T 2210/12 20130101; B60T 7/12 20130101; B60W
2520/10 20130101 |
International
Class: |
B60W 30/06 20060101
B60W030/06; B62D 15/02 20060101 B62D015/02; B60T 17/22 20060101
B60T017/22; B60T 7/12 20060101 B60T007/12 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 18, 2017 |
DE |
10 2017 216 457.3 |
Claims
1-11. (canceled)
12. A method for determining a maximum speed of a vehicle during a
parking maneuver of a parking process, comprising the following
steps: detecting at least one surroundings condition using at least
one sensor unit; supply the detected at least one surroundings
condition to a control unit as an input variable; ascertaining a
maximum possible deceleration of at least one brake circuit of a
braking system of the vehicle; and supplying the ascertained
maximum possible deceleration to the control unit as another input
variable to determine the maximum speed, the braking system
including at least two actuators for actuating a braking element,
the at least two actuators including a primary actuator and a
secondary actuator, the secondary actuator being actuated at least
in the event of a failure of the primary actuator, wherein the
maximum possible deceleration is ascertained taking a performance
capability of the secondary actuator into consideration.
13. The method as recited in claim 12, wherein the primary actuator
is used to actuate the braking element as long as a performance
capability of the primary actuator is greater than that of the
secondary actuator.
14. The method as recited in claim 12, wherein a presently possible
maximum deceleration of the at least one actuator is ascertained
based on additional information.
15. The method as recited in claim 14, wherein the additional
information includes brake wear and/or braking effect.
16. The method as recited in claim 12, wherein maximum possible
decelerations of the primary and secondary actuators are predefined
values which are stored in the control unit in the form of
characteristic maps.
17. The method as recited in claim 12, wherein the at least one
surroundings condition is an uphill grade and/or a friction
coefficient and/or a distance from an obstacle.
18. The method as recited in claim 17, wherein the at least one
surroundings condition is the uphill grade, the uphill grade being
ascertained once at a start of the parking process or, in the case
of multi-step parking maneuvers, at a start of each step of the
multi-step parking maneuvers.
19. The method as recited in claim 17, wherein the at least one
surroundings condition is the uphill grade, the uphill grade being
continuously ascertained, taking odometry data into
consideration.
20. The method as recited in claim 17, wherein in the at least one
surroundings condition is the distance from an obstacle and when no
obstacle is ascertained using a distance sensor, the range of the
distance sensor is used as the distance.
21. The method as recited in claim 12, wherein the parking process
is carried out as a fully automatic parking process.
22. The method as recited in claim 21, wherein the parking process
is terminated when a defect of the primary actuator is identified
by initiating a brake application with the maximum possible
deceleration.
23. The method as recited in claim 12, wherein an accelerator
characteristic curve is set as a function of the ascertained
maximum possible speed.
Description
FIELD
[0001] The present invention relates to a method for determining a
maximum speed of a vehicle during a parking maneuver.
BACKGROUND INFORMATION
[0002] A method is described for determining a maximum speed of a
vehicle during a parking maneuver is described in German Patent
Application No. DE 102 05 039 A1. With the aid of this method, it
is possible to generate specific accelerator characteristic curves
in such a way that, for example, an accelerator characteristic
curve is generated as a function of the maximum permissible speed
in which the internal combustion engine of the vehicle, even with a
fully depressed accelerator pedal, operates only in a partial load
operation, and thus is not able to exceed a particular maximum
speed. In this regard, the conventional method provides for
detecting detect at least one surroundings condition with the aid
of sensors and its supply as an input variable to a control unit. A
surroundings condition shall, for example, be understood to mean a
friction coefficient between the vehicle or the vehicle tire and
the roadway surface, parking surroundings, (i.e., for example, the
distance from an obstacle during a parking process) and the
detection of the vehicle inclination (downhill grade or uphill
grade of the roadway). The conventional method thus makes it
possible to limit the maximum speed during a parking process to a
maximum value, as a function of the at least one detected
surroundings condition, and to generate a corresponding accelerator
characteristic curve.
[0003] In addition, fully automated parking maneuvers are described
in the related art, in which sensor units of the vehicle detect the
size or the dimension of a parking spot and activate a steering
unit of the vehicle in such a way that the vehicle may be parked
into the parking spot. At present, it is provided, in particular,
due to legal requirements, that the driver specifies the vehicle
speed or accelerates accordingly, whereas deceleration processes
may also be carried out fully automatically, in particular, as a
function of an identified obstacle. Although, having knowledge of
the related art mentioned first, for example, a maximum permissible
vehicle speed or a corresponding accelerator characteristic curve
may be provided, the deceleration process itself, which, of course,
requires a different distance (which is taken into consideration in
the maximum possible speed) as a function of, for example, the
frictional conditions, is always based on the assumption that the
braking system of the vehicle has certain setpoint values with
respect to the possible deceleration or has its full performance
capability.
[0004] It is furthermore conventional to equip the braking system
of a vehicle with multiple brake circuits for safety reasons. At
least two actuators are used in the process, one primary actuator,
for example in the form of a hydraulic element, and one secondary
actuator, for example in the form of an electromechanical actuator,
the secondary actuator usually having a lower performance
capability than the primary actuator, and both actuators being
designed to act on one and the same braking element, in particular,
a disk brake of the vehicle, to decelerate the vehicle. Moreover,
it is conventional to use automatically the secondary actuator in
the event of failure of the primary actuator.
SUMMARY
[0005] An example method according to the present invention for
determining a maximum speed of a vehicle during a parking maneuver
may have the advantage that, in addition to at least one
surroundings condition, additionally the maximum possible
deceleration of the secondary actuator of the braking system of the
vehicle is taken into consideration. This has the advantage that a
collision of the vehicle during parking with an obstacle, for
example, may always be reliably prevented, even in the event of a
sudden failure of the primary actuator, since in this case the
vehicle may still be safely decelerated using the secondary
actuator of the braking system.
[0006] Usually, during highly automated or autonomous parking
processes, the primary actuator is generally used for decelerating
or stopping the vehicle in front of an obstacle, for example. This
main actuator has its full performance capability as long as no
defect is present. As soon as an error of the main actuator is
present, which was typically identified by appropriate software or
hardware measures, it is ensured by the secondary actuator that the
vehicle may be decelerated from the driving condition into the
standstill. The secondary actuator has a lower performance
capability than the main actuator. The lower performance capability
of the secondary actuator manifests itself, in particular, in an
extended stopping distance. In practice, such a secondary actuator
is designed as an integral part of an automatic parking brake, of
an electric brake booster or as an integral part of an ESP
system.
[0007] Advantageous refinements of the example method according to
the present invention are described herein.
[0008] One particularly preferred method in accordance with the
present invention provides that the primary actuator is used for
actuating the braking element as long as the performance capability
of the primary actuator is greater than that of the secondary
actuator. In this way, additional safety is created since the
stopping distance thus achievable is shorter than that using the
secondary actuator.
[0009] One further optimization of the example method described
thus far provides that an instantaneously possible maximum
deceleration of the at least one actuator is ascertained based on
additional information, such as the brake wear and/or the braking
effect. Such a method thusly enables an optimization in that
possible decelerations below the values stored in the control unit
or the control device are taken into consideration in the
calculation of the maximum possible parking speed.
[0010] Both the maximum deceleration of the primary actuator and,
in particular, the maximum possible deceleration of the secondary
actuator may, for example, be predefined by values stored in the
control unit. Such maximum deceleration values stored in the
control unit for the primary actuator and the secondary actuator
may, for example, be ascertained in test phases of the vehicle at
the vehicle manufacturer and be stored in the control unit, if
necessary taking additional safety margins into consideration. The
values may, in particular, be stored in the form of characteristic
maps in which the maximum possible decelerations are stored, for
example taking a particular friction coefficient or a particular
uphill grade into consideration. It is furthermore possible to
carry out a linear interpolation between adjoining stored values,
for example. Overall, stored values have the advantage that the
control unit does not need to carry out comprehensive calculations
so that a faster response time and lower costs (memory, computing
capacity for the processor) are achievable for the control device
or the control unit.
[0011] It is furthermore most particularly preferred when the at
least one surroundings condition is an uphill grade (i.e., the
roadway inclination in the area of the vehicle) and/or a friction
coefficient between a tire and the roadway surface and/or a
distance from an obstacle. All three surroundings conditions, both
individually and in combination, may have a direct influence on the
calculation of the maximum possible parking speed.
[0012] In the case of an uphill grade on which a vehicle is
situated, it is calculated with the aid of suitable units.
Thereafter, axle loads on the front and rear axles may be
ascertained based on an assumed or also measured vehicle mass, and
assuming the position of the vehicle center of gravity. These axle
loads result in maximum possible decelerations and thus, in turn,
conversely, in maximum possible speeds for the adherence to
stopping distances. In a first preferred embodiment of the example
method described last, it may be provided that the uphill grade is,
or the stopping distances are, ascertained once at the start of the
parking process or, in the case of multi-step parking maneuvers, at
the start of each step. Such an embodiment of the method, with a
respective ascertainment of the uphill grade, has the advantage
that the vehicle is at a standstill at the start of the parking
maneuver and, as a result, a particularly precise uphill grade
signal may be obtained, for example, from an acceleration sensor
since this is not distorted by accelerations of the vehicle due to
the vehicle movement.
[0013] In one alternative embodiment of the example method last
described, it may also be provided that the uphill grade is
ascertained continuously, taking the odometry data into
consideration. The odometry data may be ascertained, e.g., based on
wheel speed sensors. In this way, it is possible, for example, to
calculate an acceleration from the instantaneous speed, which may
be subtracted from an instantaneous acceleration signal to
calculate a particularly precise uphill grade. The signal may
furthermore be smoothed over time. Such a method has, in
particular, the advantage that changes in the uphill grade during
the parking maneuver are also taken into consideration, and the
safety is further enhanced thereby.
[0014] One further variant of the method according to the present
invention, taking a surroundings condition into consideration,
provides that the range of the distance sensor is used as the
distance in the case that the at least one surroundings condition
is the distance from an obstacle, and no obstacle is ascertained
with the aid of a distance sensor. Such a method has the advantage
that a maximum possible speed during the parking process may be
achieved without a decrease in safety.
[0015] The method according to the present invention described thus
far is particularly preferably used during parking processes which
are carried out as fully automatic parking processes, such parking
processes typically being characterized by a control of the speed
or of the braking process to be carried out by the driver, and, if
necessary, automatic (emergency) braking processes being initiated
in the case of identified obstacles and insufficient braking
processes carried out by the driver.
[0016] Furthermore, a fully automatic parking process within the
meaning of the present invention shall, however, additionally also
be understood to mean parking processes in which the vehicle parks
autonomously, i.e., the driver is situated outside the vehicle.
[0017] It is furthermore particularly preferred when, during an
automatic parking process, the parking process is terminated when a
defect of the primary actuator is identified by initiating a brake
application with the maximum possible deceleration. In this way, it
is signaled, in particular, also to the driver (usually in
connection with an additional visual display and/or an acoustic
warning) that the braking system does not have the full performance
capability.
[0018] One further variant of the example method described thus far
provides, with respect to a particular sensitive control of the
speed by the driver, that an accelerator characteristic curve is
set as a function of the ascertained maximum possible speed during
the parking process. What is meant here is that the maximum
possible speed may be achieved with a full actuation or depression
of the accelerator pedal in the accordingly engaged gear, but not a
speed which is higher.
[0019] Further advantages, features and details of the present
invention are derived from the following description of preferred
exemplary embodiments and based on the figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 shows a simplified illustration of a vehicle during a
fully automatic parking process.
[0021] FIG. 2 shows a block diagram to elucidate the calculation of
a maximum speed during the parking process.
[0022] FIG. 3 shows a chart to elucidate different accelerator
characteristic curves, taking different maximum parking speeds into
consideration.
[0023] Identical elements and elements having identical functions
are denoted by identical reference numerals in the figures.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
[0024] FIG. 1 shows a (fully) automated parking process of a
vehicle 1 into a parking spot 2 in a highly simplified manner.
Vehicle 1 is already situated within parking spot 2 at a distance a
from a further vehicle 3 in the reverse driving direction of
vehicle 1, vehicle 3 representing an obstacle. V.sub.max denotes
the presently maximum driving speed of vehicle 1 in the direction
toward further vehicle 3, which must not be exceeded to ensure safe
stopping of vehicle 1 within distance a prior to a collision with
further vehicle 3.
[0025] Furthermore, it is assumed for the automatic parking process
that the driver both specifies present driving speed V by a
corresponding actuation of the accelerator pedal, and brings
vehicle 1 to a standstill by an actuation of the brake. As an
alternative, it may be provided that a control unit 10 of vehicle 1
carries out a fully automatic brake application of vehicle 1,
should the driver not initiate a corresponding braking maneuver in
a timely manner or actuate the brake pedal in such a way that a
braking of vehicle 1 in front of further vehicle 3 is ensured.
[0026] FIG. 2 shows a block diagram to elucidate the calculation of
presently maximum possible speed V.sub.max of vehicle 1 during the
parking process. It is assumed in the process that vehicle 1, in
the conventional manner, includes a first sensor unit 11 for
detecting distance a from an obstacle or from further vehicle 3 in
the direction of the respective driving or parking direction.
Vehicle 10 furthermore includes a second sensor unit 12 for
detecting the driving direction or route 4. A third sensor unit 13
is designed to ascertain, for example based on an ascertained or a
detected uphill grade of the roadway on which vehicle 1 is
presently situated, the axle loads on the front axle and the rear
axle of vehicle 1. Lastly, a fourth sensor unit 14 may optionally
be provided, which is designed to ascertain a friction coefficient
p between the tire and the road or the roadway. If no fourth sensor
unit 14 is provided, the corresponding data may also be ascertained
based on other surroundings data, for example, or be stored as a
predefined value in control unit 10.
[0027] Furthermore, it is assumed that a braking system 20 of
vehicle 1 includes a primary actuator 16 and a secondary actuator
17, which (automatically) takes effect instead of primary actuator
16 in the event of a defect of primary actuator 16. Both primary
actuator 16 and secondary actuator 17 are an integral part of at
least one brake circuit of braking system 20 of vehicle 1 and act
on a braking element 24, for example on the brake disk(s) of
vehicle 1.
[0028] A first arrangement 18, which is assigned to primary
actuator 16, are used to detect the present performance capability
of primary actuator 16, for example taking the brake wear or the
braking effect into consideration. Second arrangement 19 is
assigned to secondary actuator 17 and, similarly to first
arrangement 18, is used to ascertain the present performance
capability of secondary actuator 17, in particular, the maximum
possible braking force F.sub.Brake.
[0029] FIG. 2 shows a first program block 21, which supplies
predefined data of vehicle 1, for example position of center of
gravity CG of vehicle 1 and mass M of vehicle 1, as input variables
to an algorithm 25, which is an integral part of control unit 10. A
friction coefficient p between the tires of vehicle 1 and the
roadway is ascertained within a second program block 23, or a
corresponding value is predefined. Driving direction FR and uphill
grade S of the roadway are also ascertained, each taking the
present position of vehicle 1 into consideration.
[0030] The values ascertained in second program block 23 are also
supplied to algorithm 25 as input variables. In a step 26,
algorithm 25 ascertains a maximum transmittable force F.sub.max,
which may be transmitted from vehicle 1 onto the roadway, from the
indicated input values.
[0031] A third program block 32 relates to secondary actuator 17.
In a step 33, the error recognition time is taken into
consideration which elapses until control unit 10 of vehicle 1
recognizes that primary actuator 16 has failed or has a performance
capability which is lower than the performance capability of
secondary actuator 17. In step 34, the dead time is taken into
consideration which is required for secondary actuator 17 to be
activated instead of primary actuator 16. In a step 35, the present
performance capability of secondary actuator 17, i.e., the
transmittable braking force F.sub.Brake, is subsequently
ascertained. This value is supplied to a fourth program block 43 as
an input variable.
[0032] In fourth program block 43, a possible deceleration VZ of
secondary actuator 17 is ascertained, taking maximum transmittable
force F.sub.max from step 26 into consideration.
[0033] In a subsequent fifth program block 44, a stopping distance
A may be ascertained based on present speed V and possible
deceleration VZ with the aid of secondary actuator 17. This
stopping distance A is subsequently used in a sixth program block
45 to ascertain maximum possible speed V.sub.max which vehicle 1
may presently have to enable safe stopping within available
distance a from further vehicle 3.
[0034] The ascertained maximum speed V.sub.max may be translated
into a corresponding accelerator characteristic curve 51, 52 in
accordance with the representation of FIG. 3. For elucidation, two
accelerator characteristic curves 51, 52 for different maximum
speeds V.sub.max 51 and V.sub.max 52 are shown against pedal travel
PW in the illustration in FIG. 3. In particular, it is apparent
that the driver himself or herself, with a maximally depressed
accelerator pedal in each case, is at the most able to achieve the
corresponding maximum speed V.sub.max 51 or V.sub.max 52,
accelerator characteristic curve 51, 52, as elucidated above based
on the illustration of FIG. 2, being adapted to the present
performance capability of secondary actuator 17.
[0035] The method described thus far may be altered or modified in
a variety of ways, without departing from the inventive idea. For
example, it is provided that the sensor range of first sensor unit
11 is assessed as a corresponding distance a in the event that
first sensor unit 11 does not detect an obstacle or a further
vehicle 3 in the driving direction.
* * * * *